RF ladder filter with simplified acoustic RF resonator parallel capacitance compensation

ABSTRACT

An RF ladder filter having a parallel capacitance compensation circuit is disclosed. The parallel capacitance compensation circuit is made up of a first inductive element with a first T-terminal and a first end coupled to a first ladder terminal and a second inductive element with a second T-terminal that is coupled to the first T-terminal of the first inductive element and a second end coupled to a second ladder terminal. Further included is a compensating acoustic RF resonator (ARFR) having a fixed node terminal and a third T-terminal that is coupled to the first T-terminal of the first inductive element and the second T-terminal of the second inductive element, and a finite number of series-coupled ladder ARFRs, wherein the parallel capacitance compensation circuit is coupled across one of the finite number of series-coupled ARFRs by way of the first ladder terminal and the second ladder terminal.

RELATED APPLICATIONS

The present application claims the benefits of U.S. provisional patent application No. 62/106,901 filed Jan. 23, 2015, and U.S. provisional patent application No. 62/107,852, filed Jan. 26, 2015.

The present application claims the benefit of and is a continuation-in-part of U.S. patent application Ser. No. 14/757,651 filed Dec. 23, 2015, entitled “SIMPLIFIED ACOUSTIC RF RESONATOR PARALLEL CAPACITANCE COMPENSATION,” which claims priority to U.S. provisional patent application No. 62/096,801 filed Dec. 24, 2014, and U.S. provisional patent application No. 62/109,693 filed Jan. 30, 2015.

All of the applications listed above are hereby incorporated herein by reference in their entireties.

FIELD OF THE DISCLOSURE

Embodiments of the present disclosure relate to radio frequency (RF) communications systems, which may include RF front-end circuitry, RF transceiver circuitry, RF transmit circuitry, RF receive circuitry, RF diplexers, RF duplexers, RF filters, RF antennas, RF switches, RF combiners, RF splitters, the like, or any combination thereof.

BACKGROUND

As wireless communications technologies evolve, wireless communications systems become increasingly sophisticated. As such, wireless communications protocols continue to expand and change to take advantage of the technological evolution. As a result, to maximize flexibility, many wireless communications devices must be capable of supporting any number of wireless communications protocols, each of which may have certain performance requirements, such as specific out of band emissions requirements, linearity requirements, or the like. Further, portable wireless communications devices are typically battery powered and need to be relatively small, and have low cost. As such, to minimize size, cost, and power consumption, an RF ladder filter in such a device needs to be as simple, small, flexible, high performance, and efficient as is practical. Thus, there is a need for an RF ladder filter in a communications device that is low cost, small, simple, flexible, high performance, and efficient.

SUMMARY

An RF ladder filter having a parallel capacitance compensation circuit is disclosed. The parallel capacitance compensation circuit is made up of a first inductive element with a first T-terminal and a first end coupled to a first ladder terminal and a second inductive element with a second T-terminal that is coupled to the first T-terminal of the first inductive element and a second end coupled to a second ladder terminal. Further included is a compensating acoustic RF resonator (ARFR) having a fixed node terminal and a third T-terminal that is coupled to the first T-terminal of the first inductive element and the second T-terminal of the second inductive element, and a finite number of series-coupled ladder ARFRs, wherein the parallel capacitance compensation circuit is coupled across one of the finite number of series-coupled ARFRs by way of the first ladder terminal and the second ladder terminal.

Those skilled in the art will appreciate the scope of the disclosure and realize additional aspects thereof after reading the following detailed description in association with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

FIG. 1A shows a first acoustic RF resonator (ARFR) and a load resistive element according to the prior art.

FIG. 1B illustrates a simplified behavioral model of the first ARFR illustrated in FIG. 1 according to the prior art.

FIG. 2A is a graph illustrating an electrical impedance of the first ARFR over an operating frequency ranges of the first ARFR according to the prior art.

FIG. 2B is a graph illustrating a preferred electrical impedance of the first ARFR over the operating frequency ranges of the first ARFR according to one embodiment of the present disclosure.

FIG. 3 shows RF circuitry according to one embodiment of the RF circuitry.

FIG. 4 shows the RF circuitry according to an alternate embodiment of the RF circuitry.

FIG. 5 shows details of a capacitance circuit illustrated in FIG. 4 according to one embodiment of the capacitance circuit.

FIG. 6 shows details of the capacitance circuit illustrated in FIG. 4 according to an alternate embodiment of the capacitance circuit.

FIG. 7 shows details of the capacitance circuit illustrated in FIG. 4 according to an additional embodiment of the capacitance circuit.

FIG. 8 shows the RF circuitry according to an additional embodiment of the RF circuitry.

FIG. 9 shows the RF circuitry according to another embodiment of the RF circuitry.

FIG. 10 shows the RF circuitry according to a further embodiment of the RF circuitry.

FIG. 11A shows the first ARFR and the load resistive element according to the prior art.

FIG. 11B shows the first ARFR, the load resistive element, and a first parallel capacitance compensation circuit according to one embodiment of the first ARFR, the load resistive element, and the first parallel capacitance compensation circuit.

FIG. 12A is a graph illustrating a magnitude of an RF output signal illustrated in FIG. 11A according to the prior art.

FIG. 12B is a graph illustrating a magnitude of the RF output signal illustrated in FIG. 11B according to one embodiment of the first ARFR, the load resistive element, and the first parallel capacitance compensation circuit.

FIG. 13 shows the RF circuitry according to one embodiment of the RF circuitry.

FIG. 14 shows the RF circuitry according to an alternate embodiment of the RF circuitry.

FIG. 15 shows details of the RF TX/RX multiplexer illustrated in FIG. 13 according to one embodiment of the RF TX/RX multiplexer.

FIG. 16 shows details of the RF TX/RX multiplexer illustrated in FIG. 14 according to an alternate embodiment of the RF TX/RX multiplexer.

FIG. 17A shows details of the first antenna, first RF RX bandpass filter illustrated in FIG. 15 according to one embodiment of the first antenna, first RF RX bandpass filter.

FIG. 17B shows details of the first antenna, second RF RX bandpass filter illustrated in FIG. 15 according to one embodiment of the first antenna, second RF RX bandpass filter.

FIG. 18A shows details of the first antenna, first RF RX bandpass filter illustrated in FIG. 15 according to one embodiment of the first antenna, first RF RX bandpass filter.

FIG. 18B shows details of the first antenna, second RF RX bandpass filter illustrated in FIG. 15 according to one embodiment of the first antenna, first RF TX bandpass filter.

FIG. 19A shows details of the first antenna, first RF RX bandpass filter illustrated in FIG. 15 according to one embodiment of the first antenna, first RF RX bandpass filter.

FIG. 19B shows details of the second antenna, first RF RX bandpass filter illustrated in FIG. 16 according to one embodiment of the second antenna, first RF RX bandpass filter.

FIG. 20A shows details of the first antenna, first RF TX bandpass filter illustrated in FIG. 15 according to one embodiment of the first antenna, first RF TX bandpass filter.

FIG. 20B shows details of the first antenna, second RF TX bandpass filter illustrated in FIG. 15 according to one embodiment of the first antenna, second RF TX bandpass filter.

FIG. 21A shows a portion of the RF circuitry according to one embodiment of the RF circuitry.

FIG. 21B shows a portion of the RF circuitry according to one embodiment of the RF circuitry.

FIG. 22A is a reproduction of the RF circuitry illustrated in FIG. 10.

FIG. 22B shows the RF circuitry of FIG. 22A modeled using a wye-delta transform.

FIG. 23 is a schematic of a related art ladder filter that includes a finite number of ARFRs coupled in series.

FIG. 24 is a schematic of a related art ladder filter that uses an inductor to compensate for the parallel capacitance for one of the ARFRs that comprise the related art ladder filter.

FIG. 25 is a schematic of an embodiment of a ladder filter 94 that is in accordance with the present disclosure.

FIG. 26 is a simulation plot of out of band improvements realized by the ladder filter.

FIG. 27 is a simulation plot of in band insertion loss associated with the ladder filter 94 as configured for an 8^(th) order B7 RX filter.

FIG. 28A is a schematic of RF circuitry in which the first inductor L1 and the second inductor L2 are negatively magnetically coupled.

FIG. 28B is a schematic of RF circuitry that is transformed to an equivalent bridged T network.

FIG. 28C is a schematic of RF circuitry that has been transformed from the equivalent bridged T network to an equivalent PI network.

FIG. 29A depicts a schematic model of a ladder filter that is similar to a traditional ladder filter.

FIG. 29B is a schematic of a ladder filter according to an embodiment of the present disclosure that replaces two shunt resonators of FIG. 29A.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the disclosure and illustrate the best mode of practicing the disclosure. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

RF circuitry, which includes a first acoustic RF resonator (ARFR), a first compensating ARFR, and a second compensating ARFR, is disclosed according to one embodiment of the present disclosure. The first compensating ARFR is coupled between a first inductive element and a first end of the first ARFR. The second compensating ARFR is coupled between a second inductive element and a second end of the first ARFR. The first inductive element and the second inductive element are negatively coupled to one another. The first compensating ARFR, the second compensating ARFR, the first inductive element, and the second inductive element at least partially compensate for a parallel capacitance of the first ARFR.

RF circuitry, which includes the first ARFR and the first compensating ARFR, is disclosed according to an alternate embodiment of the present disclosure. The first inductive element is coupled between the first compensating ARFR and a first end of the first ARFR. The second inductive element is coupled between the first compensating ARFR and a second end of the first ARFR. The first compensating ARFR, the first inductive element, and the second inductive element at least partially compensate for the parallel capacitance of the first ARFR. In one embodiment of the first inductive element and the second inductive element, the first inductive element and the second inductive element are negatively coupled to one another.

FIG. 1A shows a first ARFR 10 and a load resistive element RL according to the prior art. The first ARFR 10 and the load resistive element RL are coupled in series to ground to form an RF filter, which has RF bandpass filtering characteristics. The first ARFR 10 receives an RF input signal RFN and a connection between the first ARFR 10 and the load resistive element RL provides an RF output signal RFT.

FIG. 1B illustrates a simplified behavioral model of the first ARFR 10 illustrated in FIG. 1 according to the prior art. According to the simplified behavioral model, the first ARFR 10 has a series resistance RS, a series inductance LS, and a series capacitance CS coupled in series with one another. Additionally, the first ARFR 10 has a parallel capacitance CP coupled in parallel with a series combination of the series capacitance CS and the series inductance LS. As a result, the first ARFR 10 has a series resonant frequency F_(S) (FIG. 2A) and a parallel resonant frequency F_(P) (FIG. 2A).

FIG. 2A is a graph illustrating an electrical impedance of the first ARFR 10 (FIG. 1A) over an operating frequency range of the first ARFR 10 (FIG. 1A) according to the prior art. When using the first ARFR 10 (FIG. 1A) as a series element in an RF bandpass filter, preferably the series resonant frequency F_(S) falls within a passband of the RF bandpass filter and the parallel resonant frequency F_(P) falls outside of the passband of the RF bandpass filter. However, if the parallel capacitance CP (FIG. 1B) of the first ARFR 10 is large, then a bandwidth of the RF bandpass filter may be too narrow to meet design requirements. Additionally, since the parallel capacitance CP (FIG. 1B) appears primarily across the first ARFR 10 (FIG. 1A), as frequency increases, impedance of the parallel capacitance CP (FIG. 1B) drops, thereby degrading RF bandpass filtering performance at higher frequencies. Reducing the parallel capacitance CP (FIG. 1B) drives the parallel resonant frequency F_(P) to higher values. However, the power handling capabilities of the first ARFR 10 (FIG. 1A) may be reduced below requirements. Thus, there is a need to reduce the effects of the parallel resonant frequency F_(P), particularly in RF bandpass filtering applications.

One metric for quantifying bandpass filter effectiveness of the first ARFR 10 (FIG. 1A) is an RF coupling factor (k2e), which is defined as shown in EQ. 1 below. k2e=[(π/2)*(F _(S) /F _(P))]/[tan((π/2)*(F _(S) /F _(P)))].  EQ. 1:

As the parallel resonant frequency F_(P) increases relative to the series resonant frequency F_(S), k2e increases, thereby improving the bandpass filter effectiveness of the first ARFR 10 (FIG. 1A). One way to increase the parallel resonant frequency F_(P) of the first ARFR 10 (FIG. 1A) is decrease a net parallel capacitance CP (FIG. 1A) of the first ARFR 10 (FIG. 1A).

FIG. 2B is a graph illustrating a preferred electrical impedance of the first ARFR 10 (FIG. 1A) over the operating frequency ranges of the first ARFR 10 (FIG. 1A) according to one embodiment of the present disclosure. As such, a first parallel capacitance compensation circuit 12 (FIG. 3) is coupled across the first ARFR 10 (FIG. 1A) to at least partially compensate for the parallel capacitance CP (FIG. 1B) of the first ARFR 10 (FIG. 1A), thereby increasing the parallel resonant frequency F_(P) and increasing k2e.

FIG. 3 shows RF circuitry 12 according to one embodiment of the RF circuitry 12. The RF circuitry 12 illustrated in FIG. 3 includes the first ARFR 10 and a first parallel capacitance compensation circuit 14, which includes a first compensating ARFR 16, a second compensating ARFR 18, a first inductive element L1, and a second inductive element L2.

The first compensating ARFR 16 is coupled between the first inductive element L1 and a first end of the first ARFR 10. The second compensating ARFR 18 is coupled between the second inductive element L2 and a second end of the first ARFR 10. The first inductive element L1 and the second inductive element L2 have mutual coupling M between them as illustrated in FIG. 3. Further, the first inductive element L1 and the second inductive element L2 are negatively coupled to one another as illustrated in FIG. 3. The first compensating ARFR 16, the second compensating ARFR 18, the first inductive element L1, and the second inductive element L2 at least partially compensate for the parallel capacitance CP (FIG. 1B) of the first ARFR 10. In general, in one embodiment of the RF circuitry 12, the first parallel capacitance compensation circuit 14 at least partially compensate for the parallel capacitance CP (FIG. 1B) of the first ARFR 10.

The first inductive element L1 is coupled between the first compensating ARFR 16 and ground. The second inductive element L2 is coupled between the second compensating ARFR 18 and the ground. In general, in one embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 is a passive circuit, which includes no active components.

In one embodiment of the first inductive element L1 and the second inductive element L2, an absolute value of a coefficient of coupling between the first inductive element L1 and the second inductive element L2 is greater than zero. In an alternate embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is greater than 0.1. In an additional embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is greater than 0.2.

In one embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.7. In an alternate embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.6. In an additional embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.5. In another embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.4. In a further embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.3.

In one embodiment of the first inductive element L1 and the second inductive element L2, an inductance of the first inductive element L1 is essentially equal to an inductance of the second inductive element L2. In an alternate embodiment of the first inductive element L1 and the second inductive element L2, the inductance of the first inductive element L1 is not equal to the inductance of the second inductive element L2.

In one embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 augments RF bandpass filtering behavior of the first ARFR 10. In one embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 increases a ratio of the parallel resonant frequency F_(P) (FIG. 2B) to the series resonant frequency F_(S) (FIG. 2B).

In one embodiment of the first parallel capacitance compensation circuit 14 and the first ARFR 10, the first parallel capacitance compensation circuit 14 and the first ARFR 10 function as an RF bandpass filtering element, such that the parallel resonant frequency F_(P) (FIG. 2B) falls outside of a passband of the RF bandpass filtering element.

In one embodiment of the first parallel capacitance compensation circuit 14 and the first ARFR 10, the first parallel capacitance compensation circuit 14 is coupled across the first ARFR 10, such that the first parallel capacitance compensation circuit 14 presents a positive reactance across the first ARFR 10. A magnitude of the positive reactance is inversely related to frequency. Since the parallel capacitance CP (FIG. 1B) of the first ARFR 10 presents a negative reactance across the first ARFR 10, such that the negative reactance is inversely related to frequency, the positive reactance at least partially cancels the negative reactance, thereby at least partially compensating for the parallel capacitance CP (FIG. 1B) of the first ARFR 10.

In one embodiment of the first ARFR 10, the first compensating ARFR 16, and the second compensating ARFR 18, each of the first ARFR 10, the first compensating ARFR 16, and the second compensating ARFR 18 is a surface acoustic wave (SAW) RF resonator. In an alternate embodiment of the first ARFR 10, the first compensating ARFR 16, and the second compensating ARFR 18, each of the first ARFR 10, the first compensating ARFR 16, and the second compensating ARFR 18 is a bulk acoustic wave (BAW) RF resonator.

FIG. 4 shows the RF circuitry 12 according to an alternate embodiment of the RF circuitry 12. The RF circuitry 12 illustrated in FIG. 4 is similar to the RF circuitry 12 illustrated in FIG. 3, except in the RF circuitry 12 illustrated in FIG. 4, the first parallel capacitance compensation circuit 14 further includes a capacitance circuit 20. In general, the capacitance circuit 20 is coupled between the first inductive element L1 and the ground and is further coupled between the second inductive element L2 and the ground. In one embodiment of the capacitance circuit 20, the capacitance circuit 20 is used to optimize the first parallel capacitance compensation circuit 14 for improved compensation of the parallel capacitance CP (FIG. 1B) of the first ARFR 10.

FIG. 5 shows details of the capacitance circuit 20 illustrated in FIG. 4 according to one embodiment of the capacitance circuit 20. In the capacitance circuit 20 illustrated in FIG. 5, a first end of the first inductive element L1 is coupled to a first end of the second inductive element L2, such that the capacitance circuit 20 presents a shunt capacitance CN between ground and both of the first inductive element L1 and the second inductive element L2.

FIG. 6 shows details of the capacitance circuit 20 illustrated in FIG. 4 according to an alternate embodiment of the capacitance circuit 20. In the capacitance circuit 20 illustrated in FIG. 6, the second inductive element L2 is coupled between the second compensating ARFR 18 and ground, and the capacitance circuit 20 presents the shunt capacitance CN between ground and the first inductive element L1.

FIG. 7 shows details of the capacitance circuit 20 illustrated in FIG. 4 according to an additional embodiment of the capacitance circuit 20. In the capacitance circuit 20 illustrated in FIG. 7, the first inductive element L1 is coupled between the first compensating ARFR 16 and ground, and the capacitance circuit 20 presents the shunt capacitance CN between ground and the second inductive element L2.

FIG. 8 shows the RF circuitry 12 according to an additional embodiment of the RF circuitry 12. The RF circuitry 12 illustrated in FIG. 8 is similar to the RF circuitry 12 illustrated in FIG. 4, except in the RF circuitry 12 illustrated in FIG. 8, the capacitance circuit 20 is replaced with a variable capacitance circuit 22. In one embodiment of the variable capacitance circuit 22, the variable capacitance circuit 22 is used to vary the shunt capacitance CN illustrated in FIG. 5. In an alternate embodiment of the variable capacitance circuit 22, the variable capacitance circuit 22 is used to vary the shunt capacitance CN illustrated in FIG. 6. In an additional embodiment of the variable capacitance circuit 22, the variable capacitance circuit 22 is used to vary the shunt capacitance CN illustrated in FIG. 7.

In one embodiment of the variable capacitance circuit 22, the variable capacitance circuit 22 receives the first function configuration signal FCS1, such that the shunt capacitance CN is adjusted based on the first function configuration signal FCS1.

FIG. 9 shows the RF circuitry 12 according to another embodiment of the RF circuitry 12. The RF circuitry 12 illustrated in FIG. 9 includes the first ARFR 10 and the first parallel capacitance compensation circuit 14, which includes the first compensating ARFR 16, the first inductive element L1, and the second inductive element L2.

The first inductive element L1 is coupled between the first compensating ARFR 16 and a first end of the first ARFR 10. The second inductive element L2 is coupled between the first compensating ARFR 16 and a second end of the first ARFR 10. The first inductive element L1 and the second inductive element L2 have mutual coupling M between them as illustrated in FIG. 9. Further, the first inductive element L1 and the second inductive element L2 are negatively coupled to one another as illustrated in FIG. 9. The first compensating ARFR 16, the first inductive element L1, and the second inductive element L2 at least partially compensate for the parallel capacitance CP (FIG. 1B) of the first ARFR 10. In general, in one embodiment of the RF circuitry 12, the first parallel capacitance compensation circuit 14 at least partially compensate for the parallel capacitance CP (FIG. 1B) of the first ARFR 10.

The first compensating ARFR 16 is coupled between the first inductive element L1 and ground. Additionally, the first compensating ARFR 16 is further coupled between the second inductive element L2 and the ground. In general, in one embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 is a passive circuit, which includes no active components.

In one embodiment of the first inductive element L1 and the second inductive element L2, an absolute value of a coefficient of coupling between the first inductive element L1 and the second inductive element L2 is greater than zero. In an alternate embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is greater than 0.1. In an additional embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is greater than 0.2.

In one embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.7. In an alternate embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.6. In an additional embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.5. In another embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.4. In a further embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is less than 0.3.

In one embodiment of the first inductive element L1 and the second inductive element L2, an inductance of the first inductive element L1 is essentially equal to an inductance of the second inductive element L2. In an alternate embodiment of the first inductive element L1 and the second inductive element L2, the inductance of the first inductive element L1 is not equal to the inductance of the second inductive element L2.

In one embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 augments RF bandpass filtering behavior of the first ARFR 10. In one embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 increases a ratio of the parallel resonant frequency F_(P) (FIG. 2B) to the series resonant frequency F_(S) (FIG. 2B).

In one embodiment of the first parallel capacitance compensation circuit 14 and the first ARFR 10, the first parallel capacitance compensation circuit 14 and the first ARFR 10 function as an RF bandpass filtering element, such that the parallel resonant frequency F_(P) (FIG. 2B) falls outside of a passband of the RF bandpass filtering element.

In one embodiment of the first parallel capacitance compensation circuit 14 and the first ARFR 10, the first parallel capacitance compensation circuit 14 is coupled across the first ARFR 10, such that the first parallel capacitance compensation circuit 14 presents a positive reactance across the first ARFR 10. A magnitude of the positive reactance is inversely related to frequency. Since the parallel capacitance CP (FIG. 1B) of the first ARFR 10 presents a negative reactance across the first ARFR 10, such that the negative reactance is inversely related to frequency, the positive reactance at least partially cancels the negative reactance, thereby at least partially compensating for the parallel capacitance CP (FIG. 1B) of the first ARFR 10.

In one embodiment of the first ARFR 10 and the first compensating ARFR 16, each of the first ARFR 10 and the first compensating ARFR 16 is a SAW RF resonator. In an alternate embodiment of the first ARFR 10 and the first compensating ARFR 16, each of the first ARFR 10 and the first compensating ARFR 16 is a BAW RF resonator.

FIG. 10 shows the RF circuitry 12 according to a further embodiment of the RF circuitry 12. The RF circuitry 12 illustrated in FIG. 10 is similar to the RF circuitry 12 illustrated in FIG. 9, except in the RF circuitry 12 illustrated in FIG. 10, there is no intended mutual coupling M (FIG. 9) between the first inductive element L1 and the second inductive element L2. As such, the absolute value of the coefficient of coupling between the first inductive element L1 and the second inductive element L2 is essentially equal to zero.

FIG. 11A shows the first ARFR 10 and the load resistive element RL according to the prior art. The first ARFR 10 and the load resistive element RL illustrated in FIG. 11A are similar to the first ARFR 10 and the load resistive element RL illustrated in FIG. 1A.

FIG. 11B shows the first ARFR 10, the load resistive element RL, and the first parallel capacitance compensation circuit 14 according to one embodiment of the first ARFR 10, the load resistive element RL, and the first parallel capacitance compensation circuit 14. The first ARFR 10 and the load resistive element RL illustrated in FIG. 11B is similar to the first ARFR 10 and the load resistive element RL illustrated in FIG. 1A, except in FIG. 11B, the first parallel capacitance compensation circuit 14 is coupled across the first ARFR 10.

The first parallel capacitance compensation circuit 14 illustrated in FIG. 11B may include any of the embodiments of the first parallel capacitance compensation circuit 14 illustrated in FIGS. 3, 4, 5, 6, 7, 8, 9, 10, or any combination thereof.

FIG. 12A is a graph illustrating a magnitude of the RF output signal RFT illustrated in FIG. 11A according to the prior art. The magnitude of the RF output signal RFT is shown versus frequency of the RF output signal RFT. A preferred passband is illustrated. The RF output signal RFT illustrated in FIG. 12A has insufficient bandwidth to support the preferred passband. Additionally, an out of band magnitude of the RF output signal RFT increases as the frequency of the RF output signal RFT increases due to the parallel capacitance CP (FIG. 1B). As such, the first ARFR 10 and the load resistive element RL illustrated in FIG. 11A do not provide good out of band rejection of the RF output signal RFT.

FIG. 12B is a graph illustrating a magnitude of the RF output signal RFT illustrated in FIG. 11B according to one embodiment of the first ARFR 10, the load resistive element RL, and the first parallel capacitance compensation circuit 14. By adding the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 at least partially compensates for the parallel capacitance CP (FIG. 1B).

As a result, the RF output signal RFT has adequate bandwidth to support the preferred passband. Also, while the out of band magnitude of the RF output signal RFT illustrated in FIG. 12B increases as the frequency of the RF output signal RFT increases, the out of band magnitude of the RF output signal RFT illustrated in FIG. 12B is significantly less than the out of band magnitude of the RF output signal RFT illustrated in FIG. 12A.

FIG. 13 shows the RF circuitry 12 according to one embodiment of the RF circuitry 12. The RF circuitry 12 includes RF system control circuitry 24, RF front-end circuitry 26, and a first RF antenna 28. The RF front-end circuitry 26 includes an RF TX/RX multiplexer 30, RF receive circuitry 32, and RF transmit circuitry 34. The RF TX/RX multiplexer 30 has a first common connection node CN1, which is coupled to the first RF antenna 28. In one embodiment of the RF TX/RX multiplexer 30, the first common connection node CN1 is directly coupled to the first RF antenna 28. The RF system control circuitry 24 provides a first function configuration signal FCS1 to the RF front-end circuitry 26. As such, in one embodiment of the RF front-end circuitry 26, the RF system control circuitry 24 configures any or all of the RF TX/RX multiplexer 30, the RF receive circuitry 32, and the RF transmit circuitry 34 using the first function configuration signal FCS1.

In one embodiment of the RF system control circuitry 24, the RF system control circuitry 24 provides a first antenna, first upstream RF transmit signal T1U1, a first antenna, second upstream RF transmit signal T1U2, and up to and including a first antenna, M^(TH) upstream RF transmit signal T1UM to the RF transmit circuitry 34. In general, the RF system control circuitry 24 provides a group of first antenna, upstream RF transmit signals T1U1, T1U2, T1UM to the RF transmit circuitry 34.

The RF transmit circuitry 34 processes the first antenna, first upstream RF transmit signal T1U1 to provide a first antenna, first downstream RF transmit signal T1D1 to the RF TX/RX multiplexer 30, the first antenna, second upstream RF transmit signal T1U2 to provide a first antenna, second downstream RF transmit signal T1D2 to the RF TX/RX multiplexer 30, and up to and including the first antenna, M^(TH) upstream RF transmit signal T1UM to provide a first antenna, M^(TH) downstream RF transmit signal T1DM to the RF TX/RX multiplexer 30. In general, the RF transmit circuitry 34 provides a group of first antenna, downstream RF transmit signals T1D1, T1D2, T1DM to the RF TX/RX multiplexer 30.

In one embodiment of the RF system control circuitry 24, the RF system control circuitry 24 provides at least one of the group of first antenna, upstream RF transmit signals T1U1, T1U2, T1UM to the RF transmit circuitry 34, which processes and forwards any or all of the group of first antenna, upstream RF transmit signals T1U1, T1U2, T1UM to provide a corresponding any or all of the group of first antenna, downstream RF transmit signals T1D1, T1D2, T1DM to the RF TX/RX multiplexer 30. The RF TX/RX multiplexer 30 receives, bandpass filters, and forwards the corresponding any or all of the group of first antenna, downstream RF transmit signals T1D1, T1D2, T1DM to provide a corresponding any or all of a first antenna, first RF antenna transmit signal T1A1, a first antenna, second RF antenna transmit signal T1A2, and up to and including a first antenna, M^(TH) RF antenna transmit signal T1AM to the first RF antenna 28 via the first common connection node CN1.

The RF transmit circuitry 34 may include up-conversion circuitry, amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof to process any or all of the group of first antenna, upstream RF transmit signals T1U1, T1U2, T1UM. In one embodiment of the RF transmit circuitry 34, the RF transmit circuitry 34 includes circuitry to reduce interference of RF receive signals in the RF TX/RX multiplexer 30 by processing the group of first antenna, downstream RF transmit signals T1D1, T1D2, T1DM in the RF TX/RX multiplexer 30.

In one embodiment of the RF TX/RX multiplexer 30, the RF TX/RX multiplexer 30 receives any or all of a first antenna, first RF receive signal R1A1; a first antenna, second RF receive signal R1A2; and up to and including a first antenna, N^(TH) RF receive signal R1AN; which are received via the first RF antenna 28. In general, the RF TX/RX multiplexer 30 receives any or all of a group of first antenna, RF receive signals R1A1, R1A2, R1AN from the first common connection node CN1. In one embodiment of the group of first antenna, RF receive signals R1A1, R1A2, R1AN, any or all of the group of first antenna, RF receive signals R1A1, R1A2, R1AN are received simultaneously, such that the RF TX/RX multiplexer 30 supports receive downlink carrier aggregation (RXDLCA).

The RF TX/RX multiplexer 30 processes and forwards any or all of the group of first antenna, RF receive signals R1A1, R1A2, R1AN from the first common connection node CN1 to provide any or all of a first antenna, first upstream RF receive signal R1U1, a first antenna, second upstream RF receive signal R1U2, and up to and including a first antenna, N^(TH) upstream RF receive signal R1UN. In general, the RF TX/RX multiplexer 30 provides any or all of a group of first antenna, upstream RF receive signals R1U1, R1U2, R1UN to the RF receive circuitry 32.

In one embodiment of the RF receive circuitry 32, the RF receive circuitry 32 receives and processes any or all of the group of the first antenna, upstream RF receive signals R1U1, R1U2, R1UN to provide a corresponding any or all of a group of first antenna, downstream RF receive signals R1D1, R1D2, R1DN.

In an additional embodiment of the RF receive circuitry 32, the RF receive circuitry 32 simultaneously receives and processes any or all of the group of first antenna, upstream RF receive signals R1U1, R1U2, R1UN. As such, the RF receive circuitry 32 supports RXDLCA. The RF receive circuitry 32 may include down-conversion circuitry, amplification circuitry, low noise amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof.

In one embodiment of the RF front-end circuitry 26, any or all of the group of first antenna, RF receive signals R1A1, R1A2, R1AN, any or all of the group of first antenna, RF antenna transmit signals T1A1, T1A2, T1AM, any or all of the group of first antenna, upstream RF receive signals R1U1, R1U2, R1UN, any or all of the group of first antenna, downstream RF receive signals R1D1, R1D2, R1DN, any or all of the group of upstream RF transmit signals T1U1, T1U2, T1UM, and any or all of the group of downstream RF transmit signals T1D1, T1D2, T1DM are omitted.

In one embodiment of the RF system control circuitry 24, the RF system control circuitry 24 provides the first function configuration signal FCS1 to the RF TX/RX multiplexer 30, the RF receive circuitry 32, and the RF transmit circuitry 34. As such, the RF system control circuitry 24 may configure, tune, adjust, enable, disable, vary, or any combination thereof, circuits within the RF TX/RX multiplexer 30, the RF receive circuitry 32, the RF transmit circuitry 34, or any combination thereof, as necessary, using the first function configuration signal FCS1.

FIG. 14 shows the RF circuitry 12 according to an alternate embodiment of the RF circuitry 12. The RF circuitry 12 illustrated in FIG. 14 is similar to the RF circuitry 12 illustrated in FIG. 13, except the RF circuitry 12 illustrated in FIG. 14 further includes a second RF antenna 36. Additionally, the RF TX/RX multiplexer 30 further has a second common connection node CN2, which is coupled to the second RF antenna 36.

In one embodiment of the RF system control circuitry 24, the RF system control circuitry 24 further provides a second antenna, first upstream RF transmit signal T2U1, a second antenna, second upstream RF transmit signal T2U2, and up to and including a second antenna, T^(TH) upstream RF transmit signal T2UT to the RF transmit circuitry 34. In general, the RF system control circuitry 24 provides the group of first antenna, upstream RF transmit signals T1U1, T1U2, T1UM and a group of second antenna, upstream RF transmit signals T2U1, T2U2, T2UT to the RF transmit circuitry 34.

The RF transmit circuitry 34 further processes the second antenna, first upstream RF transmit signal T2U1 to provide a second antenna, first downstream RF transmit signal T2D1 to the RF TX/RX multiplexer 30, the second antenna, second upstream RF transmit signal T2U2 to provide a second antenna, second downstream RF transmit signal T2D2 to the RF TX/RX multiplexer 30, and up to and including the second antenna, T^(TH) upstream RF transmit signal T2UT to provide a second antenna, T^(TH) downstream RF transmit signal T2DT to the RF TX/RX multiplexer 30. In general, the RF transmit circuitry 34 provides the group of first antenna, downstream RF transmit signals T1D1, T1D2, T1DM to the RF TX/RX multiplexer 30 and further provides a group of second antenna, downstream RF transmit signals T2D1, T2D2, T2DT to the RF TX/RX multiplexer 30.

In one embodiment of the RF system control circuitry 24, the RF system control circuitry 24 further provides at least one of the group of second antenna, upstream RF transmit signals T2U1, T2U2, T2UT to the RF transmit circuitry 34, which processes and forwards any or all of the group of second antenna, upstream RF transmit signals T2U1, T2U2, T2UT to provide a corresponding any or all of the group of second antenna, downstream RF transmit signals T2D1, T2D2, T2DT to the RF TX/RX multiplexer 30. The RF TX/RX multiplexer 30 receives, bandpass filters, and forwards the corresponding any or all of the group of second antenna, downstream RF transmit signals T2D1, T2D2, T2DT to provide a corresponding any or all of a second antenna, first RF antenna transmit signal T2A1; a second antenna, second RF antenna transmit signal T2A2; and up to and including a second antenna, T^(TH) RF antenna transmit signal T2AT to the second RF antenna 36 via the second common connection node CN2.

The RF transmit circuitry 34 may include up-conversion circuitry, amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof to process any or all of the group of first antenna, upstream RF transmit signals T1U1, T1U2, T1UM and the group of second antenna, upstream RF transmit signals T2U1, T2U2, T2UT. In one embodiment of the RF transmit circuitry 34, the RF transmit circuitry 34 includes circuitry to reduce interference of RF receive signals in the RF TX/RX multiplexer 30 by processing the group of first antenna, downstream RF transmit signals T1D1, T1D2, T1DM and the group of second antenna, downstream RF transmit signals T2D1, T2D2, T2DT in the RF TX/RX multiplexer 30.

In one embodiment of the RF TX/RX multiplexer 30, the RF TX/RX multiplexer 30 further receives any or all of a second antenna, first RF receive signal R2A1; a second antenna, second RF receive signal R2A2; and up to and including a second antenna, P^(TH) RF receive signal R2AP; which are received via the second RF antenna 36. In general, the RF TX/RX multiplexer 30 further receives any or all of a group of second antenna, RF receive signals R2A1, R2A2, R2AP from the second common connection node CN2. In one embodiment of the group of first antenna, RF receive signals R1A1, R1A2, R1AN and the group of second antenna, RF receive signals R2A1, R2A2, R2AP, any or all of the group of first antenna, RF receive signals R1A1, R1A2, R1AN and the group of second antenna, RF receive signals R2A1, R2A2, R2AP are received simultaneously, such that the RF TX/RX multiplexer 30 supports receive downlink carrier aggregation (RXDLCA).

The RF TX/RX multiplexer 30 processes and forwards any or all of the group of second antenna, RF receive signals R2A1, R2A2, R1AP from the second common connection node CN2 to provide any or all of a second antenna, first upstream RF receive signal R2U1, a second antenna, second upstream RF receive signal R2U2, and up to and including a second antenna, P^(TH) upstream RF receive signal R2UP. In general, the RF TX/RX multiplexer 30 provides any or all of the group of first antenna, upstream RF receive signals R1U1, R1U2, R1UN and the group of second antenna, upstream RF receive signals R2U1, R2U2, R2UP to the RF receive circuitry 32.

In one embodiment of the RF receive circuitry 32, the RF receive circuitry 32 receives and processes any or all of the group of the first antenna, upstream RF receive signals R1U1, R1U2, R1UN and the group of second antenna, upstream RF receive signals R2U1, R2U2, R2UP to provide a corresponding any or all of the group of first antenna, downstream RF receive signals R1D1, R1D2, R1DN and a group of second antenna, downstream RF receive signals R2D1, R2D2, R2DP.

In an additional embodiment of the RF receive circuitry 32, the RF receive circuitry 32 simultaneously receives and processes any or all of the group of first antenna, upstream RF receive signals R1U1, R1U2, R1UN and the group of second antenna, upstream RF receive signals R2U1, R2U2, R2UP. As such, the RF receive circuitry 32 supports RXDLCA. The RF receive circuitry 32 may include down-conversion circuitry, amplification circuitry, low noise amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof.

In one embodiment of the RF front-end circuitry 26, any or all of the group of first antenna, RF receive signals R1A1, R1A2, R1AN, any or all of the group of second antenna, RF receive signals R2A1, R2A2, R1AP, any or all of the group of first antenna, RF antenna transmit signals T1A1, T1A2, T1AM, any or all of the group of second antenna, RF antenna transmit signals T2A1, T2A2, T2AT, any or all of the group of first antenna, upstream RF receive signals R1U1, R1U2, R1UN, any or all of the group of second antenna, upstream RF receive signals R2U1, R2U2, R2UP, any or all of the group of first antenna, downstream RF receive signals R1D1, R1D2, R1DN, any or all of the group of second antenna, downstream RF receive signals R2D1, R2D2, R2DP, any or all of the group of first antenna, upstream RF transmit signals T1U1, T1U2, T1UM, any or all of the group of second antenna, upstream RF transmit signals T2U1, T2U2, T2UT, any or all of the group of first antenna, downstream RF transmit signals T1D1, T1D2, T1DM, and any or all of the group of second antenna, downstream RF transmit signals T2D1, T2D2, T2DT are omitted.

FIG. 15 shows details of the RF TX/RX multiplexer 30 illustrated in FIG. 13 according to one embodiment of the RF TX/RX multiplexer 30. The RF TX/RX multiplexer 30 includes a first antenna, first RF RX bandpass filter 38, a first antenna, second RF RX bandpass filter 40, and up to and including a first antenna, N^(TH) RF RX bandpass filter 42, a first antenna, first RF TX bandpass filter 44, a first antenna, second RF TX bandpass filter 46, and up to and including a first antenna, M^(TH) RF TX bandpass filter 48. Each of the first antenna, RF bandpass filters 38, 40, 42, 44, 46, 48 illustrated in FIG. 15 is coupled to the first common connection node CN1.

In one embodiment of the first antenna, RF RX bandpass filters 38, 40, 42, each of the first antenna, RF RX bandpass filters 38, 40, 42 has a corresponding passband that is associated with a corresponding RF receive communications band. In one embodiment of the first antenna, RF TX bandpass filters 44, 46, 48, each of the first antenna, RF TX bandpass filters 44, 46, 48 has a corresponding passband that is associated with a corresponding RF transmit communications band. In one embodiment of the RF TX/RX multiplexer 30, any or all of the first antenna, RF bandpass filters 38, 40, 42, 44, 46, 48 is omitted.

In one embodiment of the first antenna, first RF RX bandpass filter 38, the first antenna, first RF RX bandpass filter 38 receives and filters the first antenna, first RF receive signal R1A1 (FIG. 13) via the first RF antenna 28 (FIG. 13) and the first common connection node CN1 to provide the first antenna, first upstream RF receive signal R1U1. In one embodiment of the first antenna, second RF RX bandpass filter 40, the first antenna, second RF RX bandpass filter 40 receives and filters the first antenna, second RF receive signal R1A2 (FIG. 13) via the first RF antenna 28 (FIG. 13) and the first common connection node CN1 to provide the first antenna, second upstream RF receive signal R1U2. In one embodiment of the first antenna, N^(TH) RF RX bandpass filter 42, the first antenna, N^(TH) RF RX bandpass filter 42 receives and filters the first antenna, N^(TH) RF receive signal R1AN (FIG. 13) via the first RF antenna 28 (FIG. 13) and the first common connection node CN1 to provide the first antenna, N^(TH) upstream RF receive signal R1UN.

In one embodiment of the first antenna, first RF TX bandpass filter 44, the first antenna, first RF TX bandpass filter 44 receives and filters the first antenna, first downstream RF transmit signal T1D1 to provide the first antenna, first RF antenna transmit signal T1A1 (FIG. 13) via first common connection node CN1 and the first RF antenna 28 (FIG. 13). In one embodiment of the first antenna, second RF TX bandpass filter 46, the first antenna, second RF TX bandpass filter 46 receives and filters the first antenna, second downstream RF transmit signal T1D2 to provide the first antenna, second RF antenna transmit signal T1A2 (FIG. 13) via first common connection node CN1 and the first RF antenna 28 (FIG. 13). In one embodiment of the first antenna, M^(TH) RF TX bandpass filter 48, the first antenna, M^(TH) RF TX bandpass filter 48 receives and filters the first antenna, M^(TH) downstream RF transmit signal T1DM to provide the first antenna, M^(TH) RF antenna transmit signal T1AM (FIG. 13) via first common connection node CN1 and the first RF antenna 28 (FIG. 13).

FIG. 16 shows details of the RF TX/RX multiplexer 30 illustrated in FIG. 14 according to an alternate embodiment of the RF TX/RX multiplexer 30. The RF TX/RX multiplexer 30 illustrated in FIG. 16 is similar to the RF TX/RX multiplexer 30 illustrated in FIG. 15 further includes a second antenna, first RF RX bandpass filter 50, a second antenna, second RF RX bandpass filter 52, a second antenna, P^(TH) RF RX bandpass filter 54, a second antenna, first RF TX bandpass filter 56, a second antenna, second RF TX bandpass filter 58, and a second antenna, T^(TH) RF TX bandpass filter 60.

Each of the first antenna, RF bandpass filters 38, 40, 42, 44, 46, 48 illustrated in FIG. 16 is coupled to the first common connection node CN1 and each of the second antenna, RF bandpass filters 50, 52, 54, 56, 58, 60 illustrated in FIG. 16 is coupled to the second common connection node CN2.

In one embodiment of the second antenna, RF RX bandpass filters 50, 52, 54, each of the second antenna, RF RX bandpass filters 50, 52, 54 has a corresponding passband that is associated with a corresponding RF receive communications band. In one embodiment of the second antenna, RF TX bandpass filters 56, 58, 60, each of the second antenna, RF TX bandpass filters 56, 58, 60 has a corresponding passband that is associated with a corresponding RF transmit communications band. In one embodiment of the RF TX/RX multiplexer 30, any or all of the second antenna, RF bandpass filters 50, 52, 54, 56, 58, 60 is omitted.

In one embodiment of the second antenna, first RF RX bandpass filter 50, the second antenna, first RF RX bandpass filter 50 receives and filters the second antenna, first RF receive signal R2A1 (FIG. 14) via the second RF antenna 36 (FIG. 14) and the second common connection node CN2 to provide the second antenna, first upstream RF receive signal R2U1. In one embodiment of the second antenna, second RF RX bandpass filter 52, the second antenna, second RF RX bandpass filter 52 receives and filters the second antenna, second RF receive signal R2A2 (FIG. 14) via the second RF antenna 36 (FIG. 14) and the second common connection node CN2 to provide the second antenna, second upstream RF receive signal R2U2. In one embodiment of the second antenna, P^(TH) RF RX bandpass filter 54, the second antenna, P^(TH) RF RX bandpass filter 54 receives and filters the second antenna, P^(TH) RF receive signal R2AP (FIG. 14) via the second RF antenna 36 (FIG. 14) and the second common connection node CN2 to provide the second antenna, P^(TH) upstream RF receive signal R2UP.

In one embodiment of the second antenna, first RF TX bandpass filter 56, the second antenna, first RF TX bandpass filter 56 receives and filters the second antenna, first downstream RF transmit signal T2D1 to provide the second antenna, first RF antenna transmit signal T2A1 (FIG. 14) via second common connection node CN2 and the second RF antenna 36 (FIG. 14). In one embodiment of the second antenna, second RF TX bandpass filter 58, the second antenna, second RF TX bandpass filter 58 receives and filters the second antenna, second downstream RF transmit signal T2D2 to provide the second antenna, second RF antenna transmit signal T2A2 (FIG. 14) via second common connection node CN2 and the second RF antenna 36 (FIG. 13). In one embodiment of the second antenna, T^(TH) RF TX bandpass filter 60, the second antenna, T^(TH) RF TX bandpass filter 60 receives and filters the second antenna, T^(TH) downstream RF transmit signal T2DT to provide the second antenna, T^(TH) RF antenna transmit signal T2AT (FIG. 14) via second common connection node CN2 and the second RF antenna 36 (FIG. 14).

FIG. 17A shows details of the first antenna, first RF RX bandpass filter 38 illustrated in FIG. 15 according to one embodiment of the first antenna, first RF RX bandpass filter 38. The first antenna, first RF RX bandpass filter 38 includes the first ARFR 10, the first parallel capacitance compensation circuit 14, a first group 62 of series-coupled ARFRs 64, and a first group 66 of shunt-coupled ARFRs 68. The first parallel capacitance compensation circuit 14 is coupled across the first ARFR 10.

The series-coupled ARFRs 64 of the first group 62 of series-coupled ARFRs 64 are coupled in series between the first ARFR 10 and the first RF antenna 28 (FIG. 13) via the first common connection node CN1. In one embodiment of the first group 66 of shunt-coupled ARFRs 68, each shunt-coupled ARFR 68 of the first group 66 of shunt-coupled ARFRs 68 is coupled between a corresponding pair of the first group 62 of series-coupled ARFRs 64 and ground. The first antenna, first RF RX bandpass filter 38 receives and filters the first antenna, first RF receive signal R1A1 (FIG. 15) via the first RF antenna 28 (FIG. 13) and the first common connection node CN1 to provide the first antenna, first upstream RF receive signal R1U1 via the first ARFR 10.

In one embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 is the first parallel capacitance compensation circuit 14 illustrated in FIG. 3, such that the first parallel capacitance compensation circuit 14 includes the first compensating ARFR 16 (FIG. 3), the second compensating ARFR 18 (FIG. 3), the first inductive element L1 (FIG. 3), and the second inductive element L2 (FIG. 3).

In an alternate embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 is the first parallel capacitance compensation circuit 14 illustrated in FIG. 4, such that the first parallel capacitance compensation circuit 14 includes the first compensating ARFR 16 (FIG. 4), the first inductive element L1 (FIG. 4), the second inductive element L2 (FIG. 4), and the capacitance circuit 20 (FIG. 4).

In an additional embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 is the first parallel capacitance compensation circuit 14 illustrated in FIG. 9, such that the first parallel capacitance compensation circuit 14 includes the first compensating ARFR 16 (FIG. 9), the first inductive element L1 (FIG. 9), and the second inductive element L2 (FIG. 9).

In another embodiment of the first parallel capacitance compensation circuit 14, the first parallel capacitance compensation circuit 14 is the first parallel capacitance compensation circuit 14 illustrated in FIG. 10, such that the first parallel capacitance compensation circuit 14 includes the first compensating ARFR 16 (FIG. 10), the first inductive element L1 (FIG. 10), and the second inductive element L2 (FIG. 10).

FIG. 17B shows details of the first antenna, second RF RX bandpass filter 40 illustrated in FIG. 15 according to one embodiment of the first antenna, second RF RX bandpass filter 40. The first antenna, second RF RX bandpass filter 40 includes a second ARFR 70, a second parallel capacitance compensation circuit 72, a second group 74 of series-coupled ARFRs 64, and a second group 76 of shunt-coupled ARFRs 68. The second parallel capacitance compensation circuit 72 is coupled across the second ARFR 70. In one embodiment of the second ARFR 70, the second ARFR 70 is similar to the first ARFR 10 illustrated in FIG. 17A. In one embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 17A.

The series-coupled ARFRs 64 of the second group 74 of series-coupled ARFRs 64 are coupled in series between the second ARFR 70 and the first RF antenna 28 (FIG. 13) via the first common connection node CN1. In one embodiment of the second group 76 of shunt-coupled ARFRs 68, each shunt-coupled ARFR 68 of the second group 76 of shunt-coupled ARFRs 68 is coupled between a corresponding pair of the second group 74 of series-coupled ARFRs 64 and ground. The first antenna, second RF RX bandpass filter 40 receives and filters the first antenna, second RF receive signal R1A2 (FIG. 15) via the first RF antenna 28 (FIG. 13) and the first common connection node CN1 to provide the first antenna, second upstream RF receive signal R1U2 via the first ARFR 10.

In one embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 3. In an alternate embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 4. In an additional embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 9. In another embodiment of the second parallel capacitance compensation circuit 72, the first parallel capacitance compensation circuit 14 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 10.

FIG. 18A shows details of the first antenna, first RF RX bandpass filter 38 illustrated in FIG. 15 according to one embodiment of the first antenna, first RF RX bandpass filter 38. The first antenna, first RF RX bandpass filter 38 illustrated in FIG. 18A is similar to the first antenna, first RF RX bandpass filter 38 illustrated in FIG. 17A.

FIG. 18B shows details of the first antenna, first RF TX bandpass filter 44 illustrated in FIG. 15 according to one embodiment of the first antenna, first RF TX bandpass filter 44. The first antenna, first RF TX bandpass filter 44 includes the second ARFR 70, the second parallel capacitance compensation circuit 72, the second group 74 of series-coupled ARFRs 64, and the second group 76 of shunt-coupled ARFRs 68. The second parallel capacitance compensation circuit 72 is coupled across the second ARFR 70. In one embodiment of the second ARFR 70, the second ARFR 70 is similar to the first ARFR 10 illustrated in FIG. 18A. In one embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 18A.

The series-coupled ARFRs 64 of the second group 74 of series-coupled ARFRs 64 are coupled in series between the second ARFR 70 and the first RF antenna 28 (FIG. 13) via the first common connection node CN1. In one embodiment of the second group 76 of shunt-coupled ARFRs 68, each shunt-coupled ARFR 68 of the second group 76 of shunt-coupled ARFRs 68 is coupled between a corresponding pair of the second group 74 of series-coupled ARFRs 64 and ground.

The first antenna, first RF TX bandpass filter 44 receives and filters the first antenna, first downstream RF transmit signal T1D1 via the second ARFR 70 to provide the first antenna, first RF antenna transmit signal T1A1 (FIG. 13) via the first common connection node CN1 and the first RF antenna 28 (FIG. 13).

In one embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 3. In an alternate embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 4. In an additional embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 9. In another embodiment of the second parallel capacitance compensation circuit 72, the first parallel capacitance compensation circuit 14 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 10.

FIG. 19A shows details of the first antenna, first RF RX bandpass filter 38 illustrated in FIG. 15 according to one embodiment of the first antenna, first RF RX bandpass filter 38. The first antenna, first RF RX bandpass filter 38 illustrated in FIG. 19A is similar to the first antenna, first RF RX bandpass filter 38 illustrated in FIG. 17A.

FIG. 19B shows details of the second antenna, first RF RX bandpass filter 50 illustrated in FIG. 16 according to one embodiment of the second antenna, first RF RX bandpass filter 50. The second antenna, first RF RX bandpass filter 50 includes the second ARFR 70, the second parallel capacitance compensation circuit 72, the second group 74 of series-coupled ARFRs 64, and the second group 76 of shunt-coupled ARFRs 68. The second parallel capacitance compensation circuit 72 is coupled across the second ARFR 70. In one embodiment of the second ARFR 70, the second ARFR 70 is similar to the first ARFR 10 illustrated in FIG. 19A.

The series-coupled ARFRs 64 of the second group 74 of series-coupled ARFRs 64 are coupled in series between the second ARFR 70 and the second RF antenna 36 (FIG. 14) via the second common connection node CN2. In one embodiment of the second group 76 of shunt-coupled ARFRs 68, each shunt-coupled ARFR 68 of the second group 76 of shunt-coupled ARFRs 68 is coupled between a corresponding pair of the second group 74 of series-coupled ARFRs 64 and ground.

The second antenna, first RF RX bandpass filter 50 receives and filters the second antenna, first RF antenna receive signal R2A1 via the second RF antenna 36 (FIG. 14) and the second common connection node CN2 to provide the second antenna, first upstream RF receive signal R2U1.

In one embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 3. In an alternate embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 4. In an additional embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 9. In another embodiment of the second parallel capacitance compensation circuit 72, the first parallel capacitance compensation circuit 14 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 10.

In one embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 3. In an alternate embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 4. In an additional embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 9. In another embodiment of the second parallel capacitance compensation circuit 72, the first parallel capacitance compensation circuit 14 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 10.

FIG. 20A shows details of the first antenna, first RF TX bandpass filter 44 illustrated in FIG. 15 according to one embodiment of the first antenna, first RF TX bandpass filter 44. The first antenna, first RF TX bandpass filter 44 illustrated in FIG. 20A is similar to the first antenna, first RF RX bandpass filter 38 illustrated in FIG. 19A. However, the first antenna, first RF TX bandpass filter 44 receives and filters the first antenna, first downstream RF transmit signal T1D1 via the first ARFR 10 to provide the first antenna, first RF antenna transmit signal T1A1 (FIG. 13) via the first common connection node CN1 and the first RF antenna 28 (FIG. 13).

FIG. 20B shows details of the first antenna, second RF TX bandpass filter 46 illustrated in FIG. 15 according to one embodiment of the first antenna, second RF TX bandpass filter 46. The first antenna, second RF TX bandpass filter 46 includes the second ARFR 70, the second parallel capacitance compensation circuit 72, the second group 74 of series-coupled ARFRs 64, and the second group 76 of shunt-coupled ARFRs 68. The second parallel capacitance compensation circuit 72 is coupled across the second ARFR 70. In one embodiment of the second ARFR 70, the second ARFR 70 is similar to the first ARFR 10 illustrated in FIG. 18A. In one embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 18A.

The series-coupled ARFRs 64 of the second group 74 of series-coupled ARFRs 64 are coupled in series between the second ARFR 70 and the first RF antenna 28 (FIG. 13) via the first common connection node CN1. In one embodiment of the second group 76 of shunt-coupled ARFRs 68, each shunt-coupled ARFR 68 of the second group 76 of shunt-coupled ARFRs 68 is coupled between a corresponding pair of the second group 74 of series-coupled ARFRs 64 and ground.

The first antenna, second RF TX bandpass filter 46 receives and filters the first antenna, second downstream RF transmit signal T1D2 via the second ARFR 70 to provide the first antenna, second RF antenna transmit signal T1A2 (FIG. 13) via the first common connection node CN1 and the first RF antenna (FIG. 13).

In one embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 3. In an alternate embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 4. In an additional embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 9. In another embodiment of the second parallel capacitance compensation circuit 72, the second parallel capacitance compensation circuit 72 is similar to the first parallel capacitance compensation circuit 14 illustrated in FIG. 10.

FIG. 21A shows a portion of the RF circuitry 12 according to one embodiment of the RF circuitry 12. The RF circuitry 12 includes an acoustic substrate 78, which includes portions of the first antenna, first RF RX bandpass filter 38 illustrated in FIG. 17A. The acoustic substrate 78 includes the first ARFR 10, the first compensating ARFR 16, the second compensating ARFR 18, the first group 62 of series-coupled ARFRs 64, and the first group 66 of shunt-coupled ARFRs 68.

FIG. 21B shows a portion of the RF circuitry 12 according to one embodiment of the RF circuitry 12. The RF circuitry 12 includes the acoustic substrate 78. The acoustic substrate 78 illustrated in FIG. 21B is similar to the acoustic substrate 78 Illustrated in FIG. 21A, except in the acoustic substrate 78 illustrated in FIG. 21B, the second compensating ARFR 18 is omitted.

FIG. 22A is a schematic of the RF circuitry 12 first illustrated in FIG. 10. The RF circuitry 12 includes the ARFR 10 and the first parallel capacitance compensation circuit 14, which includes the first compensating ARFR 16, the first inductive element L1, and the second inductive element L2.

FIG. 22B shows the RF circuitry 12 modeled by performing a wye-delta transformation on the first parallel capacitance compensation circuit 14 that is a bridged T resonator network. The wye-delta transformation yields a wye-delta model that includes a first shunt branch made up of a first impedance ZA1 in series with a first shunt ARFR 16′. A second shunt branch is made up of a second impedance ZB1 that is in series with a second shunt ARFR 16″. A third impedance ZC1 is coupled in parallel across the ARFR 10. The third impedance ZC1 tends to raise a net out of band series impedance when placed in parallel with the parallel capacitance CP (FIG. 1B) of the ARFR 10. Moreover, the third impedance ZC1 provides higher broadband cancellation of the parallel capacitance CP relative to placing an inductor in parallel with the ARFR 10.

Additionally, the first shunt branch made up of the first impedance ZA1 in series with the first shunt ARFR 16′ and the second shunt branch made up of the second impedance ZB1 in series with the second shunt ARFR 16″ provides stop band zeros and improves attenuation outside a desired passband. The first shunt ARFR 16′ and the second shunt ARFR 16″ are models of the first compensating ARFR 16.

FIG. 23 is a schematic of a related art ladder filter 80 that includes a finite number of the ARFRs 10 coupled in series. In this series-coupled configuration, each ARFR 10 is referred to as a ladder ARFR 10. The related art ladder filter 80 further includes a group of shunt branches 82 each of which are made up of a shunt ARFR 84 coupled in series with a shunt inductor 86. The shunt branches 82 are coupled between ladder nodes 88 and a fixed voltage node that is typically ground.

FIG. 24 is a schematic of a related art ladder filter 90 that uses a resonance inductor 92 to compensate for the parallel capacitance of the rightmost ARFR 10. In this case, the resonance inductor 92 is coupled across the rightmost ARFR 10. The related art ladder filter 90 provides a relatively narrow band isolation around a frequency at which the resonance inductor 92 is resonant with the parallel capacitance CP (FIG. 1B) of the ARFR 10.

FIG. 25 is a schematic of an embodiment of a ladder filter 94 that is in accordance with the present disclosure. In this embodiment, the first parallel capacitance compensation circuit 14 that was first introduced in FIG. 10 is a type of bridged T network that is coupled across the rightmost ARFR 10 by way of a first ladder terminal 96 and a second ladder terminal 98. In this particular case, the first parallel capacitance compensation circuit 14 includes the first inductive element L1 that has a first T-terminal 100 and a first end 102 coupled to the first ladder terminal 96. The second inductive element L2 has a second T-terminal 104 that is coupled to the first T-terminal 100 of the first inductive element 1 and a second end 106 that is coupled to the second ladder terminal 98. The first compensating ARFR 16 has a fixed node terminal 108 that is typically coupled to ground and a third T-terminal 110 that is coupled to both the first T-terminal 100 of the first inductive element L1 and the second T-terminal 104 of the second inductive element L2.

In this particular embodiment there is negligible mutual coupling between the first inductive element L1 and the second inductive element L2. Even so, the first parallel capacitance compensation circuit 14 provides between 10 dB and 20 dB improvement over the related art ladder filter 80, and between 5 dB and 10 dB improvement over the related art ladder filter 90 that includes the resonance inductor 92.

FIG. 26 is a simulation plot of out of band improvements realized by the ladder filter 94 as configured for an 8^(th) order band 7 (B7) receive (RX) filter. In this exemplary case, the ladder filter 94 was simulated without any mutual coupling between the first inductive element L1 and the second inductive element L2. A dashed trace in the simulation plot of FIG. 26 represents isolation provided by the related art ladder filter 80 of FIG. 23, while a dotted and dashed trace represents isolation provided by the related art ladder filter 90 of FIG. 24 that includes the inductive compensation available from the resonance inductor 92. A solid trace in the simulation plot of FIG. 26 represents isolation provided by the ladder filter 94 of the present embodiment depicted in FIG. 25. Note that isolation provided by the ladder filter 94 of the present disclosure is generally much improved relative to the isolation provided by the related art ladder filter 80 and the related art ladder filter 90 having inductance compensation 18. This exemplary embodiment has an in band insertion loss that is no greater −1.8 dB over a frequency range of about 2.6 GHz to about 2.7 GHz.

FIG. 27 is a simulation plot of in band insertion loss associated with the ladder filter 94 as configured for an 8^(th) order B7 RX filter. In this exemplary embodiment, the ladder filter 94 was simulated without any mutual coupling between the first inductive element L1 and the second inductive element L2. A dashed trace in the simulation plot of FIG. 27 represents in band insertion loss associated with the related art ladder filter 80 of FIG. 23, while a dotted and dashed trace represents in band insertion loss associated with the related art ladder filter 90 of FIG. 24 that includes the inductive compensation available from the resonance inductor 92. A solid trace in the simulation plot of FIG. 26 represents in band insertion loss associated with the ladder filter 94 of the present embodiment depicted in FIG. 25. Note that in band insertion loss associated with the ladder filter 94 of the present disclosure is generally much improved relative to the in band insertion loss associated with the related art ladder filter 80 and the related art ladder filter 90 having inductance compensation 18. The RF ladder filter 94 has an in band insertion loss is no greater −1.8 dB over a frequency range of about 2.6 GHz to about 2.7 GHz. This exemplary embodiment has an out of band isolation over a frequency range of 1.6 GHz to about 2.5 GHz that is less than about −50 dB and further has an out of band isolation over a frequency range of about 2.9 GHz to about 4.0 GHz that is less than about −60 dB.

FIG. 28A is a schematic of RF circuitry 12 in which the first inductor L1 and the second inductor L2 are negatively magnetically coupled. FIG. 28B is a schematic of RF circuitry 12 that is transformed to an equivalent bridged T network. FIG. 28C is a schematic of RF circuitry 12 that has been transformed from the equivalent bridged T network to an equivalent PI network. FIG. 28C includes a first shunt branch made up of a first impedance ZA1 in series with a first shunt ARFR 16′. A second shunt branch is made up of a second impedance ZB1 that is in series with a second shunt ARFR 16″. A third impedance ZC1 is coupled in parallel across the ARFR 10. The third impedance ZC1 tends to raise a net out of band series impedance when placed in parallel with the parallel capacitance CP (FIG. 1B) of the ARFR 10. Moreover, the third impedance ZC1 provides higher broadband cancellation of the parallel capacitance CP relative to placing an inductor in parallel with the ARFR 10.

Additionally, the first shunt branch made up of the first impedance ZA1 in series with the first shunt ARFR 16′ and the second shunt branch made up of the second impedance ZB1 in series with the second shunt ARFR 16″ provides stop band zeros and improves attenuation outside a desired passband. The first shunt ARFR 16′ and the second shunt ARFR 16″ are models of the first compensating ARFR 16.

While FIGS. 28B and 28C depict L1 and L2 as being equal, it is important to note that the first inductor L1 and the second inductor L2 do not necessarily need to be made equal in inductance value. In some instances, the inductance values for the first inductor L1 and the second inductor L2 will be required to be unequal in order to position poles and zeros for the first parallel capacitance compensation circuit 14 in order to realize a transfer function that yields maximum isolation and minimum insertion loss.

In all embodiments of FIGS. 28A, 28B and 28C, a coefficient of coupling M between the first inductor L1 and the second inductor L2 is nonzero. In one embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling M between the first inductive element L1 and the second inductive element L2 is less than 0.7. In an alternate embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling M between the first inductive element L1 and the second inductive element L2 is less than 0.6. In an additional embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling M between the first inductive element L1 and the second inductive element L2 is less than 0.5. In another embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling M between the first inductive element L1 and the second inductive element L2 is less than 0.4. In a further embodiment of the first inductive element L1 and the second inductive element L2, the absolute value of the coefficient of coupling M between the first inductive element L1 and the second inductive element L2 is less than 0.3.

The significance of the equivalent PI network depicted in FIG. 28C is that it shows that the RF circuitry 12 of FIG. 28A is usable to replace a number of shunt resonators, such as the shunt resonators 84 shown in the typical ladder filter 80 depicted in related art FIG. 23. For example an eight resonator ladder filter that has four shunt branches with four series-coupled resonators can be replaced by a six resonator ladder filter having two of the first parallel capacitance compensation circuit 14 (FIG. 28A).

In this regard, FIG. 29A depicts a schematic model of a ladder filter 112 that is similar to a traditional ladder filter, except in model ladder filter 112 in FIG. 29A, mutual coupling coefficients M1 and M2 are employed during transformation of model ladder filter 112 into a realizable ladder filter 114 that is a further embodiment of the present disclosure as depicted in FIG. 29B. In effect, the ladder filter 114 replaces one of the shunt resonators 16′ and one of the shunt resonators 16″ that are depicted in FIG. 29A. Note that in the particular embodiment of FIG. 29B, the first parallel capacitance compensation circuit 14 is coupled to every other one of the ladder resonators 10 due to shunt resonator reduction.

Some of the circuitry previously described may use discrete circuitry, integrated circuitry, programmable circuitry, non-volatile circuitry, volatile circuitry, software executing instructions on computing hardware, firmware executing instructions on computing hardware, the like, or any combination thereof. The computing hardware may include mainframes, micro-processors, micro-controllers, DSPs, the like, or any combination thereof.

None of the embodiments of the present disclosure are intended to limit the scope of any other embodiment of the present disclosure. Any or all of any embodiment of the present disclosure may be combined with any or all of any other embodiment of the present disclosure to create new embodiments of the present disclosure.

Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow. 

What is claimed is:
 1. An RF ladder filter comprising: a parallel capacitance compensation circuit having a first ladder terminal and a second ladder terminal comprising: a first inductive element with a first T-terminal and a first end coupled to the first ladder terminal; a second inductive element with a second T-terminal that is coupled to the first T-terminal of the first inductive element and a second end coupled to the second ladder terminal; and a compensating acoustic RF resonator (ARFR) having a fixed node terminal and a third T-terminal that is coupled to the first T-terminal of the first inductive element and the second T-terminal of the second inductive element; and a finite number of series-coupled ladder ARFRs, wherein the parallel capacitance compensation circuit is coupled across one of the finite number of series-coupled ARFRs by way of the first ladder terminal and the second ladder terminal.
 2. The RF ladder filter of claim 1 wherein the fixed node terminal of the compensating ARFR is coupled to an RF ground node.
 3. The RF ladder filter of claim 2 further including shunt arms coupled at nodes between the series-coupled ladder ARFRs and the RF ground, wherein each of the shunt arms comprises a shunt ARFR coupled in series with a shunt inductor.
 4. The RF ladder filter of claim 3 wherein the parallel capacitance compensation circuit electrically replaces two of the shunt arms of a standard ladder filter having shunt arms coupled at every one of the nodes between the series-coupled ladder ARFRs.
 5. The RF ladder filter of claim 1 further including additional ones of the parallel capacitance compensation circuit individually coupled across every other one of the finite number of series-coupled ladder ARFRs.
 6. The RF ladder filter of claim 1 wherein the first inductive element and the second inductive element are negatively coupled to one another.
 7. The RF ladder filter of claim 1 wherein the parallel capacitance compensation circuit comprises the compensating ARFR, the first inductive element, and the second inductive element, such that the parallel capacitance compensation circuit is a passive circuit, which comprises no active components.
 8. The RF ladder filter of claim 1 wherein an absolute value of a coefficient of coupling between the first inductive element and the second inductive element is essentially equal to zero.
 9. The RF ladder filter of claim 1 wherein an absolute value of a coefficient of coupling between the first inductive element and the second inductive element is greater than zero and less than 0.7.
 10. The RF ladder filter of claim 1 wherein an inductance of the first inductive element is not equal to an inductance of the second inductive element.
 11. The RF ladder filter of claim 1 wherein the parallel capacitance compensation circuit is configured to increase a ratio of a parallel resonant frequency of the series-coupled ladder ARFR to a series resonant frequency of the series-coupled ladder ARFR to which the parallel capacitance compensation circuit is coupled across.
 12. The RF ladder filter of claim 11 wherein the parallel capacitance compensation circuit and the series-coupled ladder ARFR to which the parallel capacitance compensation circuit is coupled across are configured to function together as an RF bandpass filtering element, such that the parallel resonant frequency falls outside of a passband of the RF bandpass filtering element.
 13. The RF ladder filter of claim 1 wherein a parallel capacitance compensation circuit is configured to present a positive reactance across the series-coupled ladder ARFR to which the parallel capacitance compensation circuit is coupled across, wherein a magnitude of the positive reactance is inversely related to frequency.
 14. The RF ladder filter of claim 1 wherein each of the series-coupled ladder ARFR to which the parallel capacitance compensation circuit is coupled across and the compensating ARFR is a surface acoustic wave (SAW) RF resonator.
 15. The RF ladder filter of claim 1 wherein each of the series-coupled ladder ARFR to which the parallel capacitance compensation circuit is coupled across and the compensating ARFR is a bulk acoustic wave (BAW) RF resonator.
 16. The RF ladder filter of claim 1 further comprising an acoustic substrate, which comprises the series-coupled ladder ARFR and the compensating ARFR, wherein the acoustic substrate includes the first ladder terminal and the second ladder terminal.
 17. The RF ladder filter of claim 1 wherein an in band insertion loss is no greater than −1.8 dB over a frequency range of about 2.6 GHz to about 2.7 GHz.
 18. The RF ladder filter of claim 1 wherein an out of band isolation over a frequency range of 1.6 GHz to about 2.5 GHz is less than about −50 dB.
 19. The RF ladder filter of claim 1 wherein an out of band isolation over a frequency range of about 2.9 GHz to about 4.0 GHz is less than about −60 dB. 